Freeze drying has been a very successful technology in the food and pharma industries, particularly owing to the benefits it offers in terms of product quality. It is most recommended for high value foods and those that contain heat-sensitive ingredients. Over the years, to meet industry requirements, several variants of the freeze drying technology have been developed, even to meet specific drying applications. The process of freeze drying is highly energy-intensive and time-consuming. Nevertheless, innovative techniques are available with the potential to produce products at reduced drying times and lower cost, whilst being environment-friendly and maintaining freeze dried quality. This review summarizes advances in the application of infrared, microwave, ultrasound, pulsed electric field, and other techniques as pre-treatments and/or to assist conventional freeze drying processes. Freeze drying combined with other techniques can provide more benefits in terms of energy, time, and cost savings. The most important benefit is that it can maintain the quality of the end-product by conserving its sensorial properties and retaining more nutrients.In this review article, comparative studies have been presented to describe these aspects. Such techniques to assist the freeze drying process can be linked well with sustainable food processing strategies, particularly considering a significant reduction in energy requirements.
Summary
Chia oil is a popular source of ω‐3 fatty acids, typically α‐linolenic acid. This study reports the encapsulation of chia oil in nanoliposome to protect ω‐3 fatty acids and to obtain a sustained release of chia oil during digestion. Nanoliposomal encapsulation was carried out using solvent evaporation, followed by sonication. The encapsulation process was conducted using different lipid contents, with different concentrations of soy phosphatidylcholine (S), Tween 80 (T) and volumes of the aqueous phase. The maximum encapsulation efficiency was found to be 88.31%, and the average particle size was 49.25 nm; a moderate repulsion among the particles was observed. Differential scanning calorimetry study revealed enhanced thermal stability of chia oil in nanoliposomes. A negligible release (3.39%) of encapsulated chia oil was observed in the simulated gastric fluid, and a 74.72% sustained release was recorded in the simulated intestinal fluid. This formulation can be a suitable supplement of ω‐3 fatty acids for food and therapeutic applications.
Present study was conducted to evaluate the effect of Power ultrasound, on dehulling efficiency, dhal yield, dehulling loss and total colour difference of black gram using response surface methodology. Nine treatments were performed with variation in ultrasound power 343-525 W and treatment time 1-3.5 h. It was observed that ultrasound treatment significantly improved the dehulling efficiency and dhal yield of the black gram and reduced the dehulling loss. The optimized treatment condition obtained for optimum dehulling yield (75.71%), dhal yield (74.63%) dehulling loss (12.72%), and total colour difference (5.08) was ultrasound power of 513.39 W and exposure time of 2.12 h. Moreover the blackgram pretreated with ultrasound required lesser cooking time when compared to soaked alone sample. The SEM analysis revealed the significant effect of ultrasound on the blackgram kernel which led to uniform cavitation of the surface of the kernel compared to the soaked sample without ultrasound treatment. In food industry blackgram is preprocessed i.e. soaked and cooked to produce various soups, canned products, batter, snack foods etc. Hence ultrasonic treatment can be applied to improve and facilitate a faster dehulling efficiency, with added advantage of increased soaking rate and a decrease in the cooking time for blackgram.
In the present study, setting time, apparent viscosity and water‐holding capacity for Indian Curd was optimized by using central composite design, where process variable were amplitude level (20–100%, i.e., 11.6 μm–58 μm) and treatment time (5–30 min for treatment before inoculation and 5–15 min for treatment after inoculation). It was observed that ultrasound amplitude and treatment time significantly affected the response variables. The optimum condition for ultrasound treatment before inoculation was identified as 69.43% amplitude and 14.12 min treatment time for minimum curd setting time 5.46 hr., maximum apparent viscosity 24.53 Pa.s and maximum water‐holding capacity 75.79%. The optimum condition for ultrasound treatment after inoculation was identified as 51.46% amplitude level and 9.74 min treatment time for minimum curd setting time 3.40 hr., maximum apparent viscosity 12.12 Pa.s and maximum water‐holding capacity 66.69%. Fermentation kinetics was studied, using Weibull model for optimized condition obtained from RSM. It was found that ultrasound significantly affected the kinetic parameter, that is, rate constant (K) which was maximum for sample treated with ultrasound after inoculation followed by the sample treated with ultrasound before inoculation and control sample (R2 > 80%).
Practical Applications
This result has a significant potential to be used in the dairy industry for curd formation, as ultrasound pretreatment can significantly decrease the curd fermentation/gelation time, save time and increase the production efficiency. Consumption of Curd is correlated to improved gut microflora which eventually leads to good health. Hence curd is an important diet across the globe. Industrial production of curd generally requires 5 hrs or more for fermentation. In this regard present study identified and confirmed a novel method of curd processing using power ultrasound treatment which could not only improve the quality of curd but also accelerate the rate of fermentation for curd formation. Further this study has established a kinetic model for fermentation of curd, which has the potential to be utilized by dairy industry for curd production, thus saving time and increasing the production efficiency and profit.
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